Process for producing a urethane-modified polyisocyanurate foam

ABSTRACT

A process for producing a urethane-modified polyisocyanurate foam having excellent characteristics such as flame retardancy, heat resistance and low smoking property, and further having improved initial adhesion, particularly adhesion after a relatively long period of time, to a facing material particularly a flexible facing material, by using water as a blowing agent, is provided. A polyisocyanate compound component, a polyol component, water and a morpholine compound are reacted in the presence of a trimerization catalyst for isocyanates.

TECHNICAL FIELD

The present invention relates to a process for producing a foam havingexcellent characteristics such as flame retardancy, heat resistance andlow smoking property, and having improved initial adhesion to a facingmaterial, without using specific flon (“chlorofluorocarbon”, hereinafterreferred to simply as “CFC”) or a flon substitute(“hydrochlorofluorocarbon”, hereinafter referred to simply as “HCFC”).

BACKGROUND ART

Heretofore, urethane-modified polyisocyanurate foams have been known asheat insulating materials excellent in flame retardancy, heat resistanceand low smoking property. In this case, it has been essential to replaceCFCs and HCFCs used as a blowing agent because of a problem of depletingthe ozone layer, and a production process using water as a blowing agentsubstitute (i.e. carbon dioxide gas generated when water and apolyisocyanate are reacted acts as a blowing agent) has been studied. Ina case where water is used as a blowing agent, in a case of continuousproduction of e.g. laminate boards or metal sidings, the initialadhesion to a facing material tends to decrease, and thus variousimprovements have been attempted, but no satisfactory result has beenobtained.

Further, with respect to the initial adhesion in production process,there are problems in adhesion at the time of cutting in an extremelyshort period of time (within 5 minutes after initiation of foaming) andadhesion at the time of cutting and handling of a product in the process(after a relatively long period of time, i.e. within about 30 minutesafter initiation of foaming), and particularly a decrease in adhesionafter a relatively long period of time has been problematic. Forexample, Japanese Patent No. 2972523 discloses improvement in initialadhesion by use of a fatty acid phosphate containing no halogen,however, adhesion after a relatively long period of time significantlydecreases, such being problematic. Japanese Patent Application2000-199501 discloses improvement in initial adhesion by use of acompatibilizing agent, however, adhesion after a relatively long periodof time significantly decreases similarly in most cases, such beingproblematic.

A schematic drawing illustrating a change with time of adhesion to afacing material, particularly a flexible facing material, in a case ofproduction of e.g. a laminate board or a metal siding using aurethane-modified polyisocyanurate foam as a core, is shown in FIG. 1.From 1 to 2 minutes after removal from a mold, the adhesion is at least1 kg/10 cm width (peeling test, the same applies hereinafter), however,after from 30 to 60 minutes, the adhesion reaches the minimum. As timefurther passes, the final adhesion recovers to at least 1 kg/10 cmwidth, however, the time when the adhesion reaches the minimum overlapswith a time when a product is handled in many cases, and peeling of afacing material tends to take place, thus leading to difficulty inproduction. The above tendency is particularly remarkable when thedensity of the foam is decreased. It is an object of the presentinvention to provide a urethane-modified polyisocyanurate foam havingexcellent characteristics such as flame retardancy, heat resistance andlow smoking property, and further having improved initial adhesion,particularly adhesion after a relatively long period of time, to afacing material particularly a flexible facing material, which employswater as a blowing agent and which employs no CFCs or HCFCs.

DISCLOSURE OF THE INVENTION

The present inventors have conducted extensive studies on improvement ininitial adhesion, particularly adhesion after a relatively long periodof time, to a facing material particularly a flexible facing material,while maintaining excellent characteristics such as flame retardancy,heat resistance and low smoking property, by using water as a blowingagent for production of a urethane-modified polyisocyanurate foam, andas a result, they have found that a morpholine compound improves initialadhesion, particularly adhesion after a relatively long period of time,to a flexible facing material, and the present invention has beenaccomplished on the basis of this discovery.

Namely, the present invention provides a process for producing aurethane-modified polyisocyanurate foam, which comprises reacting apolyisocyanate compound component (A), a polyol component (B), water(C), a foam stabilizer (D) and a morpholine compound (E), in thepresence of a trimerization catalyst (F). Further, the present inventionis characterized in that the morpholine compound (E) is used in anamount of from 1 to 20 parts by weight based on 100 parts by weight ofthe polyol component (B), the foam stabilizer (D) is used in an amountof from 0.5 to 5 parts by weight based on 100 parts by weight of thepolyol component (B), the trimerization catalyst (F) is used in anamount of from 0.35 to 15 parts by weight based on 100 parts by weightof the polyol component (B), and water (C) is used in an amount of from2 to 30 parts by weight based on 100 parts by weight of the polyolcomponent (B).

Further, the present invention is characterized in that the morpholinecompound (E) is one or two or more members selected from morpholine,N-methylmorpholine and N-ethylmorpholine, the polyol component (B)contains a benzylic ether type phenolic resin and/or a modified phenolicresin obtained by reacting a polyhydric alcohol or its alkylene oxideadduct with a benzylic ether type phenolic resin, the foam stabilizer(D) is an organic polysiloxane copolymer, the trimerization catalyst (F)is a trimerization catalyst for isocyanates, comprising an organic metalsalt or a tertiary amine salt, and the trimerization catalyst (F) isused together with a urethane-forming catalyst.

The process for producing a urethane-modified polyisocyanurate foam ofthe present invention employs a morpholine compound which is anitrogen-containing type and a cyclic ether type, and accordingly evenwhen water is used as a blowing agent, the produced foam has excellentcharacteristics such as flame retardancy, heat resistance and lowsmoking property, and in addition, has improved initial adhesion,particularly adhesion after a relatively long period of time, to afacing material particularly a flexible facing material.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1: A diagram illustrating a change with time of adhesion to afacing material particularly a flexible facing material in a case ofproduction of e.g. a laminate board or a metal siding using aurethane-modified polyisocyanurate foam as a core.

BEST MODE FOR CARRYING OUT THE INVENTION

The polyol component used in the present invention is a mixture ofpolyols generally used for production of a urethane foam. Examples ofthe polyols include ethylene glycol, diethylene glycol, polyethyleneglycol, propylene glycol, dipropylene glycol, polypropylene glycol,polytetramethylene glycol, 1,4-butanediol or these difunctional polyolsaddition-polymerized with one or two or more kinds of alkylene oxides,trifunctional polyols such as trimethylolpropane, glycerin or thesetrifunctional polyols addition-polymerized with one or two or more kindsof alkylene oxides, polyfunctional polyols such as pentaerythritol,sorbitol, sugar or these polyfunctional polyols addition-polymerizedwith one or two or more kinds of alkylene oxides, alkanolamineaddition-polymerized with one or two or more kinds of alkylene oxides,an aromatic polyester polyol and an acryl polyol resin.

Further, as the polyols, a phenolic resin, a modified phenolic resin,benzylic ether type phenolic resin, and a modified phenolic resinproduced by a method as disclosed in JP-B-7-30156 (from 20 to 100 partsby weight of a polyhydric alcohol or its alkylene oxide adduct is addedto 100 parts by weight of a benzylic ether type phenolic resin, followedby heating under reduced pressure), may also be mentioned. They may beused alone or in a mixture of two or more.

The polyisocyanate compound used in the present invention is notparticularly limited and may be one generally used for production of apolyurethane foam, examples of which include m- or p-phenylenediisocyanate, p-xylene diisocyanate, ethylene diisocyanate,tetramethylene-1,4-diisocyanate, hexamethylene-1,6-diisocyanate,diphenylmethane-4,4′-diisocyanate, 3,3-dichloro-4,4′-biphenylenediisocyanate or 1,5-naphthalene diisocyanate, 2,4- and 2,6-tolylenediisocyanate and their mixture, crude tolylene diisocyanate,4,4′-diphenylmethane diisocyanate, and crude diphenylmethanediisocyanate. These isocyanate compounds may be used alone or in amixture of two or more. Its amount used is an equivalent ratio of anisocyanate group to active hydrogen in a polyol component mixturesolution containing water in a range of from 1.50 to 10.0, preferablyfrom 1.70 to 4.50. If the above equivalent ratio is less than 1.50,flame retardancy, heat resistance and low smoking property become poor,and if it is more than 10.0, a foam produced becomes brittle andadhesion to a facing material becomes poor.

The morpholine compound used in the present invention has conventionallybeen used as a urethane-forming catalyst, however, it works as acompatibilizing agent in the process for producing a urethane-modifiedpolyisocyanurate foam of the present invention. It may, for example, bemorpholine, N-methylmorpholine or N-ethylmorpholine. They may be usedalone or in a combination of two or more. Its amount used is preferablyfrom 1 to 20 parts by weight, particularly preferably from 1.0 to 10parts by weight, based on 100 parts by weight of the polyol component(B).

As the foam stabilizer used in the present invention, an organicpolysiloxane copolymer generally used as a foam stabilizer in productionof a urethane foam may be used as it is. Examples of the organicpolysiloxane copolymer include SH-190, SH-192, SH-193, SH-194, M-505,M-507, M-509 and SRX253 manufactured by Toray Silicone K.K., L-520,L-540, L-580, L-582, L-5340, L-5410, L-5420, L-5470 and SZ-1127manufactured by UNICAR CO., LTD., TFA-4200, TFA-4205 and TFA-7241manufactured by Toshiba Silicone K.K., and B-8404 and B-8017manufactured by GOLDSCHMIDT K.K. Further, as the foam stabilizer used inthe present invention, a mixture of silicone type surfactants havingdifferent surface tensions as disclosed in Japanese Patent Application2000-361130 may be mentioned. In this case, foams having a low densityand a high density can be obtained.

The amount of the foam stabilizer used in the present invention ispreferably from 0.5 to 5 parts by weight, particularly preferably from1.0 to 3.0 parts by weight, based on 100 parts by weight of the polyolcomponent (B).

The trimerization catalyst used in the present invention may be atrimerization catalyst for isocyanates used in production of e.g. aconventional polyisocyanurate resin. Examples of the trimerizationcatalyst include organic metal salt systems such as potassium acetate,potassium octenate and iron oxalate, and tertiary amine salts such as2,4,6-tris(dimethylaminomethyl)-phenol andN,N′,N″-tris(dimethylaminopropyl)hexahydrotriamine. In the presentinvention, an urethane-forming catalyst may be used together with thetrimerization catalyst.

In the present invention, the trimerization catalyst, or theurethane-forming catalyst and the trimerization catalyst, are used in anamount of preferably from 0.35 to 15 parts by weight, particularlypreferably from 0.70 to 10 parts by weight based on 100 parts by weightof the polyol component (B).

The urethane-forming catalyst used in the present invention, i.e. acatalyst used for carrying out urethane-foaming reaction may be onegenerally known as a urethane-forming catalyst, examples of whichinclude N,N,N′,N′-tetramethylethylenediamine,N,N,N′,N′-tetramethylpropane-1,3-diamine, N,N,N′,N′-tetramethylhexene-1,6-diamine,N,N,N′,N″,N″-pentamethyldiethylenetriamine, N,N-dicyclohexylmethylamine,bis (N,N-dimethylaminoethylpiperazyl)ethane,N,N′,N″-tris(diethylaminopropyl)hexahydrotriazine and other tertiaryamine, and dibutyltin dilaurate and dibutyltin diacetate. Thesecatalysts may be used alone or in a mixture thereof.

Water used in the present invention reacts with a polyisocyanatecompound to produce carbon dioxide gas and works as a blowing agent. Theamount of water is determined depending on an aimed density of a foam,and is suitably from 2 to 30 parts by weight based on 100 parts byweight of the polyol component (B). If the amount of water is less than2 parts by weight, the density of a foam becomes too high, and if itexceeds 30 parts by weight, the mechanical strength becomes too low forpractical use. Particularly, the amount of water used is preferably from2.5 to 15 parts by weight based on 100 parts by weight of the polyolcomponent (B).

In the present invention, if necessary, a flame retardant or acrosslinking agent may be used. Examples of the flame retardant includetriphenyl phosphate, tricresyl phosphate, trichloroethyl phosphate,triethyl phosphate and tris-β-chloroethyl phosphate, and they may beused alone or in a combination of two or more. Examples of thecrosslinking agent include ethylene glycol, propylene glycol,1,4-butanediol, 1,6-hexanediol, diethylene glycol, triethylene glycol,triethanolamine and ethylenediamine, and they may be used alone or in acombination. These additives and other additives may be previously mixedwith a mixture containing the polyol component (B) or may be addedthereto at the time of reacting.

Now, the present invention will be explained specifically with referenceto Examples and Comparative Examples. “Part(s)” and “%” are based onweight. The density was measured in accordance with JIS A-9514 using afoam obtained by free-foaming. As an initial adhesion test, foaming inthe form of a board was carried out by attaching a PE (polyethylene)coat kraft paper as a facing material to an aluminum made frame of400×300×25 mm heated at 60° C., and after 1 and a half minutes hadpassed, the obtained foam was released from the frame, and a peelingtest with a width of 10 cm was carried out after one minute and after 30minutes to measure the adhesion.

EXAMPLE 1

20 parts of BEP (manufactured by Hodogaya Chemical Co., Ltd., modifiedphenolic resin OH value: 620), 50 parts of PL-180 (manufactured by TohoRika K.K., aromatic polyester polyol OH value: 190), 10 parts of SOR400(manufactured by Takeda Chemical Industries, Ltd., sorbitol typepolyether polyol OH value: 395), 20 parts of SOR200 (manufactured byTakeda Chemical Industries, Ltd., sorbitol type polyether polyol OHvalue: 200), 10 parts of tris-(monomethyl-2-chloropropyl)phosphate(hereinafter referred to simply as TMCPP, manufactured by DAIHACHICHEMICAL INDUSTRY CO., LTD., flame retardant), 15 parts of triethylphosphate (hereinafter referred to simply as TEP, manufactured by BayerLtd., flame retardant), 5 parts of N-ethylmorpholine (hereinafterreferred to simply as NEMO, manufactured by Wako Pure ChemicalIndustries, Ltd.), 1.9 parts of TSF-4452 (manufactured by ToshibaSilicone K.K., foam stabilizer), 0.15 part of TSF-451-50 (manufacturedby Toshiba Silicone K.K., foam stabilizer), 6 parts of water, 5 parts ofPELCAT9540 (manufactured by Pelron Co., trimerization catalyst) and 0.4part of TOYOCAT DT (manufactured by TOSOH CORPORATION, urethane-formingcatalyst) were mixed, and 281 parts of MR-100 (manufactured by NipponPolyurethane Industry Co., Ltd., crude diphenylmethane diisocyanate, NCOcontent: 31.0%) was added thereto, followed by stirring, and the mixturewas transferred to a 1 l paper cup for foaming. The obtained foam was ina favorable foam state, and had a density of 26.5 kg/m³.

As an initial adhesion test, the above mixture was subjected to foamingin the form of a board by attaching a PE coat kraft paper as a facingmaterial to an aluminum made frame of 400×300×25 mm heated at 60° C.,and after one and a half minutes had passed, the obtained foam wasreleased from the frame, and a peeling test with a width of 10 cm wascarried out after one minute and after 30 minutes, and results of atleast 1.0 kg were obtained respectively.

EXAMPLES 2 to 7

Foaming was carried out in the same manner as in Example 1 except thatthe amount of NEMO used was changed, and the density was measured andthe initial adhesion test was carried out. The measurement results areshown in Table 1.

TABLE 1 Examples 1 2 3 4 5 6 7 Polyol (1) 100 100 100 100 100 100 100TMCPP 10 10 10 10 10 10 10 TEP 15 15 15 15 15 15 15 Water 6 6 6 6 6 6 6TFS-4452 1.9 1.9 1.9 1.9 1.9 1.9 1.9 TSF-451-50 0.15 0.15 0.15 0.15 0.150.15 0.15 PELCAT9540 5 5 5 5 5 5 5 TOYOCAT-DT 0.4 0.4 0.4 0.4 0.4 0.40.4 NEMO 5 3 2 1 3 2 1 DMF 0 5 5 5 0 0 0 MR-100 281 281 281 281 281 281281 NCO/OH 1.75 1.75 1.75 1.75 1.75 1.75 1.75 equivalent ratio Density(kg/m³) 26.5 26 27.1 26.3 26.5 26.4 26.7 Adhesion (kg/10 cm) 1 min.after 1< 1< 1< 1< 1< 1< 1< 30 min. after 1< 1< 1< 1< 1< 1< 1<

Starting materials employed were as follows.

-   -   Polyol (1): 20 parts of BEP (manufactured by Hodogaya Chemical        Co., Ltd., modified phenolic resin OH value: 620), 50 parts of        PL-180 (manufactured by Toho Rika K.K., aromatic polyester        polyol OH value: 190), 10 parts of SOR400 (manufactured by        Takeda Chemical Industries, Ltd., sorbitol type polyether polyol        OH value: 395), 20 parts of SOR200 (manufactured by Takeda        Chemical Industries, Ltd., sorbitol type polyether polyol OH        value: 200), TMCPP: tris-(monomethyl-2-chloropropyl)phosphate        (manufactured by DAIHACHI CHEMICAL INDUSTRY CO., LTD., flame        retardant)    -   TEP: triethyl phosphate (manufactured by Bayer Ltd., flame        retardant)    -   NEMO: N-ethylmorpholine (manufactured by Wako Pure Chemical        Industries, Ltd.)    -   TSF-4452: organic polysiloxane copolymer (manufactured by        Toshiba Silicone K.K., foam stabilizer)    -   TSF-451-50: organic polysiloxane copolymer    -   PELCAT9540: trimerization catalyst (manufactured by Pelron Co.)    -   TOYOCAT DT: urethane-forming catalyst (manufactured by TOSOH        CORPORATION)    -   DMF: dimethylformamide    -   DMAC: dimethyl acetamide    -   DMSO: dimethyl sulfoxide    -   MR-100: crude diphenyl methane diisocyanate (manufactured by        Nippon Polyurethane Industry Co., Ltd.)

COMPARATIVE EXAMPLES 1 to 7

Foaming was carried out in the same manner as in Example 1 except thatNEMO in the composition of Example 1 was changed to another compound,and the density was measured and the initial adhesion test was carriedout. The results are shown in Table 2. An adhesion after one minute ofat least 1 kg/10 cm was obtained, however, the adhesion after 30 minuteswas so low as at most 0.5 kg/10 cm width in any Comparative Example, andit is found that a morpholine is excellent in view of the initialadhesion (after a relatively long period of time) as compared withanother compatibilizing agent.

TABLE 2 Comparative Examples 1 2 3 4 5 6 7 Polyol (1) 100 100 100 100100 100 100 TMCPP 10 10 10 10 10 10 10 TEP 15 15 15 15 15 15 15 Water 66 6 6 6 6 6 TFS-4452 1.9 1.9 1.9 1.9 1.9 1.9 1.9 TSF-451-50 0.15 0.150.15 0.15 0.15 0.15 0.15 PELCAT9540 5 5 5 5 5 5 5 TOYOCAT-DT 0.4 0.4 0.40.4 0.4 0.4 0.4 NEMO 0 0 0 0 0 0 0 DMF 5 0 0 0 0 0 0 TEP 0 5 0 0 0 0 0DMAC 0 0 5 0 0 0 0 Butyl acetate 0 0 0 5 0 0 0 N-methyl pyrrolidone 0 00 0 5 0 0 Acetonitrile 0 0 0 0 0 5 0 DMSO 0 0 0 0 0 0 5 MR-100 281 281281 281 281 281 281 NCO/OH 1.75 1.75 1.75 1.75 1.75 1.75 1.75 equivalentratio Density (kg/m³) 26 27.2 26.8 26.4 26.3 26.7 26.4 Adhesion (kg/10cm) 1 min. after 1< 1< 1< 1< 1 1 1< 30 min. after 0.4 0.2 0.5 0.2 0.20.1 0.1

INDUSTRIAL APPLICABILITY

According to the present invention, a process for producing aurethane-modified polyisocyanurate foam having excellent characteristicssuch as flame retardancy, heat resistance and low smoking property, andfurther having improved initial adhesion, particularly adhesion after arelatively long period of time, to a facing material particularly aflexible facing material, by using water as a blowing agent without useof CFCs or HCFCs, can be provided.

1. A process for producing a urethane-modified polyisocyanurate foam,which comprises reacting a polyisocyanate compound component (A), apolyol component (B), water (C), a foam stabilizer (D) and a morpholinecompound (E), in the presence of a trimerization catalyst (F), whereinthe above morpholine compound (E) is one or two or more members selectedfrom the group consisting of morpholine, N-methylmorpholine andN-ethylmorpholine, and wherein the polyol component (B) contains abenzylic ether phenolic resin and/or a modified phenolic resin obtainedby reacting a polyhydric alcohol or its alkylene oxide adduct with abenzylic ether phenolic resin.
 2. The process for producing aurethane-modified polyisocyanurate foam according to claim 1, whereinthe above morpholine compound (E) is used in an amount of from 1 to 20parts by weight based on 100 parts by weight of the polyol component(B).
 3. The process for producing a urethane-modified polyisocyanuratefoam according to claim 1, wherein the above trimerization catalyst (F)is used in an amount of from 0.35 to 15 parts by weight based on 100parts by weight of the polyol component (B).
 4. The process forproducing a urethane-modified polyisocyanurate foam according to claim1, wherein the above water (C) is used in an amount of from 2 to 30parts by weight based on 100 parts by weight of the polyol component(B).
 5. The process for producing a urethane-modified polyisocyanuratefoam according to claim 1, wherein the above foam stabilizer (D) is usedin an amount of from 0.5 to 5 parts by weight based on 100 parts byweight of the polyol component (B).
 6. The process for producing aurethane-modified polyisocyanurate foam according to claim 1, whereinthe above foam stabilizer (D) is an organic polysiloxane copolymer. 7.The process for producing a urethane-modified polyisocyanurate foamaccording to claim 1, wherein the above trimerization catalyst (F) is atrimerization catalyst for isocyanates, comprising an organic metal saltor a tertiary amine salt.
 8. The process for producing aurethane-modified polyisocyanurate foam according to claim 1, whereinthe above trimerization catalyst (F) is used together with aurethane-forming catalyst.
 9. A urethane-modified polyisocyanurate foamprepared by the process of claim 1.